Ignition magneto provided with a rotary cylindrical magnet



Nov. 30, 1943. J. BERNARD 2,335,378

IGNITION MAGNETO PROVIDED WITH ROTARY CYLINDRICAL MAGNETS Filed June 29, 1940 2 Sheets-Sheet l .57 Man o; 'Jjerna Nov. 30, 1943.

J. BERNARD 2,335,378

IGNITION MAGNETO PROVIDED WITH ROTARY CYLINDRICAL MAGNETS Filed June 29, 1940 2 Sheets-Sheet 2 Patented Nov. 30,

IGNITION MAGNE'IO PROVIDED WITH A ROTARY CYLINDRICAL MAGNET Jean Bernard, Paris, France; vested in the Alien Property Custodian -Application June'29, 1940, Serial No. 343,283

4 In France July 3, 1939 6Claims.

My invention relates to ignition magnetos for internal combustion engines in which the rotary flux distributor member comprises a cylindrical magnet rotatable about its axis and on the pole pieces of which are fitted laminated plates which are arranged to form a spider and successively act on the pole pieces of the armature.

My invention has for one of its objects improvements in this type of magneto, and particularly to the circuit of the magnetic flux conductor pieces in order to improve the use of the flux of the magnet and to increase the efficiency of the magneto.

Another object of my invention is to provide a substantially cylindrical field magnet with means allowing the whole flux of said magnet to flow at a substantially constant magnetic potential.

My invention has for a further object the provision of an improved mounting of the ignition coil on the frame of magneto.

These and other objects will more particularly appear from the following description taken in connection with the accompanying drawings, illustrating, by way of example, a preferred form of my invention and in which:

Fig. 1 is a section taken transversely to the axis of the rotor on the line II of Fig. 2, and

Fig. 2 is a longitudinal section taken on the line 11-11 of Fig. 1.

Figs. 3 and 4 respectively show an end view and a partial section along the line IV-IV of Fig. 3, of a modification of the field magnet.

In the embodiment shown in Figs. 1 and 2, the tubular cylindrical magnet I is fitted by its pole pieces in circular recesses 2 of solid flux conductors 3 made of a magnetic metal such as mild steel. The ends of said recesses are provided with plane faces applied against the pole faces of the magnet. Through this assembly there passes axially-a shaft 4 made of non-magnetic metal, which passes freely through the central hole of the magnet I and is fitted in bores of the solid conductors 3. The known means consisting of a shoulder 5 on said shaft 4 and a nut 6 adapted to screw on said shaft is used for locking said assembly in position.

Said conductors 8 are each constituted by a central plate carrying at its periphery a rim which is not in contact with the magnet. The said rim is outwardly limited by a cylindrical surface on which are fitted laminated fiux distributors 8 which are axially held at one end by an outer flange or shoulder 9 of said rim and by a crimping It at the opposite end and are prevented from rotating on said rim by projections I I which are fitted half into the laminations and half in the conductor 3. The inner surface of the rim is shaped'approxlmately like the lateral surface of alfrustum of a cone tapering outwardly from the p ate.

The plates forming the laminated distributors 8 are shaped like rings, from the outer periphery of which extend radial arms I! which may be of any number, four per distributor in the present example. The arms of one distributor are displaced 45 with respect to the arms of the other distributor.

Opposite the two distributors 8 and embedded in the frame, are arranged two pairs of armature masses i8, H. The masses are formed by laminated plates perpendicular to the axis of the armature, the masses which are opposite the same distributor being arranged symmetrically with respect to a plane passing through the axis of the field magnet. The masses emerge from the frame and are limited by plane surfaces It and I1. Two U-shaped magnetic conductors I 9, which are independent of the frame are pressed against the surfaces It and I1, each of said conductors being thus in contact with masses of unlike polarity. Each magnetic conductor I9, is laminated parallel to the axis of the field magnet and the constituent plates thereof are carefully insulated and assembled by a means which prevents circuits that cause eddy currents, for example by means of insulated rivets such as the rivets 20. The magnetic conductors I! support the coil 2|, the core 22 of which may rest on them in any known manner or, preferably and as shown, by fitting the cylindrical ends of the core in the likewise cylindrical bearings provided in said conductors IS. The plates constituting said conductors are in this case provided with holes for locating said core. Said holes are open at the top in order to prevent the formation of closed circuits about the core. The bridge formed by the two conductors and the coil is removable and is held in position by means of insulated screws 23 which pass through the core 22 of the coil and screw into portions of the frame between the armature masses l3 and H. The said screws act both to maintain the coil and the two conductors.

From the magnetic standpoint in the circuit thus described, the various elements of unlike polarity are at a distance from each other which is determined experimentally according to the armature reaction of the coil, so that the magnetic distortion shall remain substantially constant.

In the field magnet, the distance between the two laminated distributors and the length of the distributor arms relatively to the. circular crosssection are calculated in this manner. Similarly, for the conical inner part of the solid flux conductors, the distance betweezrsaid conductors and the magnet increases towards the centre of the magnet, to a value which gives a suitablemaa= netic leakage path.

According to the modification shown in Figs. 3 and 4, the outer surface of the rim of each of the solid flux conductors 3 is cylindrical and has no projection such as 9 or ill according to Figs. 1 and 2. The two laminated distributors 8 are clamped on a common intermediate ring made of a non-magnetic metal, by means of rivets, screws or bolts 3i which are likewise made of non-magetic metal. Said two distributors thus form, with said ring 3d, a rigid assembly which is forced, either in the hot state, or on a press, on to the outer cylindrical surface of the rim of the solid conductors 3. Projections M, which are fitted as stated above, prevent said assembly from rotating relatively to the rim.

Finally, a projection connecting the shoulder 5 to the solid conductor 3 ensures the drive of the latter and of all the laminated distributors 8 by the shaft d. i a

Under these conditions, the magnetic attracting force which is exerted by the fixed armature masses l3 and M (Fig. l) on the distributors 8 during the rotation of the field magnet, and which is liable to displace the distributors 8 angularly relatively to each other, is not supported by the shaft 4 and there is no danger of such '5 a relative displacement.

While I have illustrated and described what I at present consider the preferred form of construction for carrying my invention into effect, this is capable of variation and modification, without departing from the spirit of the invention, I therefore do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

What I claim is:

1. In an ignition magneto, a field magnet mounted for rotation about an axis and including a magnet coaxial with said axis provided with plane pole ends substantially. perpendicular with said axis, two solid conductors made of magnetic metal associated with the two pole ends respectively and each comprising a central plate and a rim, said central plate being provided with a plane face applied against the corresponding plane pole end of the magnet, said rim being not in contact with the magnet and being outwardly limited by a continuous annular surface coaxial with said axis, and flux distributors formed by laminated plates substantially perpendicular with said axis, and these flux distributors being all mounted on said rims to have their inner edges in contact with the corresponding annular surface.

2. In an ignition magneto, a rotary field magnet including a shaft made of non-magnetic metal, a magnet coaxial. with said shaft, this magnet being provided with an exial central bore of a diameter slightly greater than the diameter of said shaft and with plane pole ends substantially perpendicular with said axis, two solid conductors made of magnetic metal cooperating with the two pole ends respectively and carried by said shaft, each of said conductors including a central plate and a rim,'the central plate being provided with a circular recess in which the corresponding end of the magnet is fitted, the bottom of said recess being plane and applied against the corresponding pole end, said rim being not in contact with the magnet and being outwardly limited by a continuous annular surface and fiux distributors formed by laminated plates substantially perpendicular with said axis and these flux distributors being all mounted on said rims to have their inner edges in contact with the corresponding annular surface.

3. In an ignition magneto, a field magnet mounted for rotation about an axis and including a magnet coaxial with said axis provided with plane pole ends substantially perpendicular with said axis, two solid conductors made of magnetic metal associated with the two pole ends respectively and each comprising a central plate and a rim, said central plate being provided with a plane face applied against the corresponding plane pole end of the magnet, said rim being not in contact with the magnet and being outwardly limited by a continuous annular surface coaxial with said axis, two fiux distributors formed by laminated plates substantially perpendicular with said axis and mounted on said rims so as to have their inner edges in contact with the corresponding annular surface, a ring of non-magnetic metal coaxial with said axis and arranged between said flux distributors, and means for clamping said flux distributors on said ring.

4. An ignition magneto as claimed in claim 3 including a driving shaft for said field magnet, means for keying and centering said conductors on said shaft, said magnet being provided with a central bore of a diameter greater than the diameter of said shaft and means for locking said magnet with reference to said conductors.

5. In an ignition magneto, a field magnet mounted for rotation about an axis which is the magnetic axis of the two magnetic poles, said magnet having plane pole ends substantially perpendicular to said axis, two solid conductors of magnetic metal associated with the two pole ends respectively and each comprising a central plate and a rim, each of said central plate being provided with a plane face applied against the corresponding plane pole end of th magnet, each of said rims being in the form of a cylindrical member integral with the central plate and being outwardly limited by a continuous annular surface co-axial with said axis, said two rims extending from the central plates toward each other and thus partially surrounding said magnet, and flux distributors formed by laminated plates substantially perpendicular with respect to said axis, said flux distributors being all mounted on said rims with their inner edges in contact with the corresponding annular surface whereby magnetic lines from each of the two ends of said magnet extend through the respective central plate and rim and thence radially through the magnetic distributors.

6. Apparatus as described in claim 5 wherein a ring of non-magnetic material bridges the gap between the adjacent edges of the two rims and the associated flux distributors, and a non-magnetic clamping means holding the assemblies formed by the solid conductors and the associated distributors against the spaced sides of the ring of non-magnetic material.

JEAN BERNARD. 

